Moderator role of vitamin D concentrations on the association between metabolic syndrome and C-reactive protein among adults

ABSTRACT Objective To evaluate the association between MetS, its components and insulin resistance (IR) with 25(OH)D and hsCRP. The moderator role of 25(OH)D in the association of MetS, its diagnostic components and IR with hsCRP were also explored. Materials and methods A cross-sectional study (2014/2015) with a population-based cohort in Southern Brazil (n = 605). Metabolic syndrome (MetS) diagnosis was defined based on the Joint Interim Statement, while the Homeostasis Model Assessment of insulin resistance (IR) (HOMA-IR) was used for determining IR. Serum concentrations of 25-hydroxy vitamin D [25(OH)D] (ng/mL) and high sensitivity C-reactive protein (hsCRP) (mg/L) were evaluated following standard protocols. 25(OH)D was categorized as sufficiency (>30 ng/mL), insufficiency (20-30 ng/mL) or deficiency (<20 ng/mL) to test its moderator role. Multiple linear regression was used to test the associations. The results were adjusted for possible confounders. Results and discussion Hypertriglyceridemia and IR were associated with lower 25(OH)D concentrations. However, except for systolic blood pressure, other MetS components and IR were associated with higher hsCRP. The association between elevated waist circumference (WC) and hsCRP was moderated by the 25(OH)D concentrations. The hsCRP median concentrations were more than two times higher among those with elevated WC and 25(OH)D insufficiency or deficiency. In this study, inadequate concentrations of 25(OH)D increased the adverse relationship between elevated WC and inflammation. 25(OH)D concentrations could be incorporated into the clinical protocols for monitoring individuals with abdominal obesity to identify those at a higher risk of complications.

Serie de Redacción Científica: Estudio de Casos y Controles / Scientific Writing Series: Case-Control studies

Introducción: Un estudio de casos y controles es un estudio en el que se compara individuos que tuvieron un desenlace de interés o outcome (casos) versus individuos que no tuvieron dicho resultado (controles) con respecto a la exposición de interés, potencialmente un "factor de riesgo" o "factor de protección". El objetivo de un estudio de casos y controles es primariamente determinar si existe asociación entre una exposición (o varias) y un desenlace de interés. Esta asociación debe ser cuantificada y reportada como un odds ratio o razón de momios teniendo en cuenta sus fortalezas y limitaciones. En general, este tipo de estudios ofrece como ventajas su relativo bajo costo y rapidez con la que es posible realizarlos. Sin embargo, no son idóneos si lo que se quiere investigar son desenlaces de interés frecuente o con periodos de latencia largos. En el presente artículo se han revisado las principales consideraciones metodológicas del diseño de los estudios de casos y controles esperando con ello contribuir objeto de promover su correcta utilización e interpretación.

Introduction: A case-control study is a study comparing individuals who had an outcome of interest (cases) versus individuals who had no such outcome (controls) with respect to the exposure of interest, potentially a "risk factor "or" protection factor." The objective of a case-control study is primarily to determine if there is an association between one exposure (or several) and an outcome of interest. This association must be quantified and reported as an odds ratio or odds ratio taking into account its strengths and limitations. In general, this type of study offers as advantages its relatively low cost and speed with which it is possible to carry them out. However, they are not ideal if what you want to investigate are frequent outcomes or with long latency periods. In this article, the primary methodological considerations of the design of case-control studies have been reviewed, hoping thereby to contribute to promoting their correct use and interpretation.